Organic electroluminescence displays (OELDs) have been applied more and more to flat panel displays in recent years due to the merits of lightness and thinness, wide viewing angle, fast response speed, high contrast, and so on. The technology of combining a blue-emitting OELD with a color conversion material is one of the technologies for realizing full color OELD, and color conversion materials currently used are mainly inorganic doped system materials that can be excited by blue light, such as, (1) Ce doped yttrium aluminum garnet; (2) Eu doped alkaline earth metal silicate; (3) silicon-based nitride or oxynitride doped with rare earth ions. However, these color conversion materials usually have problems of lower color purity and efficiency.
Quantum Dots (QDs) can also be called as nano-crystalline, for example, and are a kind of nano particles composed of group II-VI or group III-V elements. The grain size of quantum dots generally lies between 1 nm and 20 nm; because electrons and holes contained therein are quantum-confined, a continuous energy band structure is converted into a discrete energy level structure showing molecular properties, and fluorescence can be emitted after the particles are excited.
The emission spectrum of quantum dots can be controlled by modifying the size of quantum dots. By means of modifying the size of a quantum dot and its chemical composition, its emission spectrum can be expanded to cover the whole visible region. With a CdTe quantum dot as an example, when its grain size is increased from 2.5 nm to 4.0 nm, its emission wavelength may be subjected to redshift from 510 nm to 660 nm.
Both the fluorescent intensity and stability of quantum dots are good. At present, with the light-emitting property of quantum dots, quantum dots may function as molecular probes in the application of fluorescence marking, and quantum dots may also be applied to display devices, serving as light emitting sources of a backlight module of a liquid crystal display panel. Light emitted from a quantum dot after it is excited by blue light mixes with the blue light, so as to produce white light. The white light has a larger gamut, so that the picture quality can be enhanced. However, there is still not a design in which quantum dots are applied to an electroluminescence display device in prior art.